Merge remote-tracking branch 'remotes/rth/tags/pull-tcg-20151201' into staging

Last minute fix

# gpg: Signature made Tue 01 Dec 2015 22:37:25 GMT using RSA key ID 4DD0279B
# gpg: Good signature from "Richard Henderson <rth7680@gmail.com>"
# gpg:                 aka "Richard Henderson <rth@redhat.com>"
# gpg:                 aka "Richard Henderson <rth@twiddle.net>"

* remotes/rth/tags/pull-tcg-20151201:
  tcg: Increase the highwater reservation

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

tcg/tcg.c

@@ -388,7 +388,11 @@ void tcg_prologue_init(TCGContext *s)
     /* Compute a high-water mark, at which we voluntarily flush the buffer
        and start over.  The size here is arbitrary, significantly larger
        than we expect the code generation for any one opcode to require.  */
-    s->code_gen_highwater = s->code_gen_buffer + (total_size - 1024);
+    /* ??? We currently have no good estimate for, or checks in,
+       tcg_out_tb_finalize.  If there are quite a lot of guest memory ops,
+       the number of out-of-line fragments could be quite high.  In the
+       short-term, increase the highwater buffer.  */
+    s->code_gen_highwater = s->code_gen_buffer + (total_size - 64*1024);
 
     tcg_register_jit(s->code_gen_buffer, total_size);